Double ductor



G. R. BRODIE DOUBLE DUCTOR Dec. 24, 1968 Filed March 22, 1967 INVENTOR. GEORGE R. BRODI E their ATTORNEYS. 7 V

United States Patent O 3,417,692 DOUBLE DUCTOR George R. Brodie, Narberth, Pa., assignor to John C. Motter Printing Press (10., York, Pa., a corporation of Delaware Filed Mar. 22, 1967, Ser. No. 625,257 2 Claims. (Cl. 101-350) ABSTRACT OF THE DISCLOSURE A ductor for the ink distributing apparatus of a printing press comprising a pair of spaced-apart, rotatable ductor rolls mounted in the space between the fountain roll and the first distribution roll for movement of each roll alternately with the other between contact with the fountain roll and contact with the first distribution roll such that the ductor rolls alternately transfer ink from the fountain roll to the first distribtuion roll. Each of the ductor rolls has a surface constituted by a series of spaced, raised ink transfer portions and recesses between the transfer portions, the transfer portions of one ductor roll being staggered with respect to the transfer portions of the other.

Background of the invention This invention relates to a novel and improved double ductor for the inking system of a printing press.

The inking systems of printing presses, notably of the offset or letterpress type, are composed of a series of distribution rolls, some of which are vibrated longitudinally, that spread and smooth ink applied by a ductor to the first roll in the series from a fountain roll. The fountain roll rotates at a low speed relative to the rate of rotation of the distribution rolls and picks up ink from the reservoir (or fountain). A ductor roll oscillates back and forth between contact with the fountain roll to pick up ink from it and contact with the first distribution roll to transfer the ink to the first distribution roll.

In some inking systems, the ductor is composed of two ductor rolls straddling the space between the fountain roll and the first distribution roll and arranged to oscillate in a manner by which each ductor roll, in alternation with the other, is moved between contact with thefountain roll and contact with the first distribution roll. A ductor constituted by two ductor rolls is often referred to, and is referred to hereinafter, as a double ductor. Double ductors have the advantage of being able to operate at a lower rate of reciprocation; with relatively high speed presses single ductor rolls must move back and forth so rapidly that a number of complications in operation are introduced. Double ductors, because they are reciprocated at lower speeds, are usually preferred for high speed presses.

It is advantageous to provide for variation in the rate of rotation of the fountain roll of an offset press inking system to provide control over ink transfer. With a double ductor, however, it is impossible to vary the rate of rotation of the fountain roll outside of a limited range, because each ductor roll will contact part of the fountain roll from which ink has already been removed by the other ductor roll. When this happens, the ductor operates unpredictably and does not respond properly to steps taken by the operator to adjust the ink supply to the plate. This difficulty constitutes a significant limitation on the versatility of presently known double ductors, because it significantly restricts control over the inking and makes it difiicult, at best, to obtain a uniform, high quality product.

Summary of the invention There is provided, in accordance with the present invention, a novel and improved inking system which overcomes the :problem of limited ink control and loss of predictable operation in previously known double ductor inking systems and permits a double ductor to be used while, nonetheless, the inking system is operated under optimum conditions without any restrictions on the rate of rotation of the fountain roll and the rate of oscillation of the ductor imposed by the ductor. More particularly, the two rolls of the ductor have surfaces constituted by a series of spaced-apart, raised ink transfer portions and recesses between the transfer portions. The transfer portions of one ductor roll are staggered with respect to the transfer portions of the other ductor roll, thus providing transfer portions on the respective rolls which are out of phase or registration with each other. Because the transfer surfaces of the respective ductor rolls are out of phase, there is no possibility under any operating conditions of either ductor striking a portion of the fountain roll from which ink has been previously removed by the other, inasmuch as the transfer surfaces of the respective rolls track portions of the fountain roll that are substantially independent of each other. Accordingly, the ductor of the invention ensures that virgin surfaces of the fountain roll will always be presented for ink pickup by the respective ductor rolls.

Brief description of the drawings For a better understanding of the invention, reference may be made to the following description of an exemplary embodiment, taken in conjunction with the figures of the accompanying drawings, in which:

FIG. 1 is a partial front elevational view of the double ductor, the ductor being illustrated with the fountain roll and the first distribution roll of the inking system removed for clearer illustration and only a typical portion at one end being shown to avoid unnecessary repetition; and

FIG. 2 is a view in end section of the ductor taken generally along the line 2-2 of FIG. 1 and in the direction of the arrows. 1

Description of exemplary embodiment The ductor of the invention is useful with various specific designs of ink fountains and ink distribution systems and, accordingly, the details of these elements of the press inking apparatus are not shown in the drawings or described in detail. Segments of the ink fountain roll and first distribution roll are shown, however, as designated by the reference numerals 10 and 12, respectively. The fountain roll 10 receives a film of ink by immersion of a portion of its surface in a reservoir of ink (not shown). The ink is picked up onto the surface and then is wiped to provide a film of the desired quantity by an adjustable blade (not shown).

The ductor of the invention, which is designated generally by the reference numeral 14, is composed of a pair of spaced-apart ductor rolls 16 and 18 carried at either end by oscillatory carrier members 20, only one of which is illustrated in the partial elevational view of FIG. 1. The carrier members 20 are bolted to shafts 22 journaled in the press frames 24, and each has two oval-shaped mounting holes 26 and 28 to receive eccentrics and bearing carrier members 30 and 32, which are preferably of the quick-opening type to facilitate removal and replacement of the ductor rolls 16 and 18. The bearing carriers 30 and 32 are mounted in the eccentrics, which afford adjustment of the positions of the ductor rolls relative to the fountain roll and first distribution roll, and carry bearings (not shown) in which the shafts 16a and 18a of the respective ductor rolls are journaled. Adjusting screws 34 and 336 permit further adjustment of the respective rolls 16 and 18 relative to the fountain roll 10 and first distribution roll 12. Mounted at one end of the ductor carrier member 20 is a cam follower 38 which is received in the track 40 of a rotary box cam 42.

The cam 42 is designed to impart oscillatory movement to the mounting member 20, and thus to the ductor rolls 16 and 18, to bring the respective rolls 16 and 18, in alternation with each other, into contract first with the fountain roll 10 to pick up a film of ink from the fountain roll and then into contact with the first distribution roll of the ink distribution system to transfer the ink to it.

The ductor rolls 16 and 18 are preferably constructed of tubular base members 50 and 52, respectively, end members 54 and 56 formed with shafts 16a and 18a, and rubber covering elements 58 and 60. In accordance with the invention, the surfaces of the rolls, that is, the rubber coverings 58 and 60, are formed with raised bands 58a and 60a and grooves or recesses 58b and 6%, respectively. The raised bands 58a and 60a contact the surfaces of the fountain roll 10 and the first distribution roll 12 to the exclusion of the recesses 58b and 60b, which are of a depth sufficient to ensure that they will not touch the fountain roll or the first distribution roll. Thus, the raised bands 58a and 60a constitute transfer portions of the ductor roll surfaces.

The raised bands 58a and 60a of both rolls are preferably all of equal width and are also equal in width to the recesses 58b and 601). For example, the width of the raised bands 58a and 60a and the recesses 58b and 60b may be inch. The bands and recesses of the respective rolls 16 and 18 are staggered or out of phase with each other so that the bands 58a on one ductor roll 16 will track rings on the fountain roll between those tracked by the bands 60a of the other ductor roll 18. In this manner, each of the ductor rolls has a surface constituted by spaced-apart raised portions which track bands on the fountain roll and distribution roll which are independent and substantially non-overlapping.

In operation, the fountain roll is driven in the direction indicated by the arrow at a relatively slow speed, the speed being variable to control the amount of ink transfer. The cam 42 is driven at a speed such that it provides the desired frequency of oscillation of the duetor. During each revolution of the cam 42, the ductor carrier members are oscillated back and forth about their pivot mounting shafts 22 to in sequence (1) bring the upper ductor 16 into engagement with the fountain roll and (2) at the same time move the lower ductor roll 18 into engagement with the distribution roll 12, (3) move the upper ductor roll 16 into engagement with the distribution roll 12 and (4) at the same time bring the lower ductor roll 18 into engagement with the fountain roll. Thus, each revolution of the cam results in two ducts, one by each of the ductor rolls 16 and 18.

As the upper ductor roll 16 dwells in contact with the fountain roll 10 for a predetermined time, it is driven by the fountain roll and picks up a film of ink on the raised transfer bands 58a. Meanwhile, the ink previously deposited on the transfer surfaces 60a of the lower ductor roll 18 are transferred onto the first distribution roll 12. During phases (3) and (4), supra, of the cycle of operation, the ink is transferred from the transfer bands 58a on the roll 16 to the distribution roll 12 while the ductor roll 18 picks up ink from the fountain roll.

It is important to note that the rate of rotation of the fountain roll can be varied without regard to the ductor cycle and yet will not at any time result in skipping inasmuch as the ink transfer portions of the respective ductor rolls track difierent, circumferentially spaced rings on the fountain roll. Thus, the ductor of the invention provides the advantage of considerably greater versatility of operation of the ink distribution system by permitting variation of the rate of rotation of the fountain roll 10 to obtain the desired ink transfer. In addition, the conductor of the invention retains all of the advantages of known double ductors.

The above-described embodiment of the invention is intended to be merely exemplary, and those skilled in the art will be able to make numerous variations and modifications of it without departing from the spirit and scope of the invention. All such variations and modifications are intended to be included within the scope of the invention as defined in the appended claims.

I claim:

1. In a printing press inking system having an ink fountain roll and a first ink distribution roll spaced from the fountain roll, the combination therewith of a ductor comprising a pair of spaced rotatable ductor rolls straddling the space between the fountain roll and the first distribution roll and mounted for oscillatory movement of each roll alternately with the other between contact with the fountain roll and contact with the first distribution roll to transfer ink from the fountain roll to the first distribution roll, the surfaces of each of the ductor rolls being constituted by a series of spaced-apart raised ink transfer portions and recesses between the transfer portions, and the transfer portions of one ductor roll being staggered with respect to the transfer portions of the other roll, whereby the transfer portions of each ductor roll track virgin inked portions of the fountain roll regardless of the operating speed of the fountain roll.

2. An ink distribution apparatus according to claim 1 wherein the raised transfer portions and the recessed portions of each roll are in the form of bands of equal width centered on planes perpendicular to the axes of the respective rolls.

References Cited UNITED STATES PATENTS 1,207,258 12/1916 Wood 101-350 2,083,542 6/1937 Barber 101-35O 2,141,607 12/1938 Lamatsch 101-350 2,693,755 11/1954 Fitchett et al 101350 ROBERT E. PULFREY, Primary Examiner.

F. A. WINANS, Assistant Examiner.

US. Cl. X.R. 29l30. 

